Process for preparing i



Feb. 25, 1958 ENDE. GILBERT ETAL Re- PRocEss Foa PREPARING EcAcHLoRoTETRAHYDRo-4,'r-METHANOINDENEON) A HYDROLYZED REACTION PRODUCT 0F HExAcHLoRocYcLoPENTADIENE 2 Sheets-Sheet 2 AND SULFUR TRIOXIDE Original Filed Nov. 1'7, 1950 AT TORN EY y Nolsuwsnvui .maand United States Patent O PROCESS FOR PREPARING [DECACHLORO- TETRAHYDRO.4,7-METHANOINDENEONE] A HYDROLYZED REACTION PRODUCT OF Re. 24,435 .-Reissued "Feb, 25, 1958 ICC The drawings, Figs. l1-4 inclusive, represent 'infrared spectrograms of the [decachlorotetrahydro-4,7methano indeneone] ketonic compound prepared' according to our invention, and of certain of its reaction products with HEXACHLOROCYCLOPENTADIENE AND 5 other organic compounds- SULFUR. TRIOXIDES' In the drawings, Fig. 1 represents the infrared spectro- Evelelt E G llb'elt, M OIPS TUYllShlP, Mol'Yl'jS Cfmltys gram of the [decachlorotetrahydro-4,7methanoindene- N ll Sllrl) [Glhflg WlteSt0DeiN- assmis One,] ketonic compound, as obtained in carbon disulfide g; Y im oeranil of Ne'eYofpora on ew or solution, the several lines showing the spectrograms reo '.na'l No rg 616 928 dated November 4 1952 Seal 10 corded of samples of different degrees. of hydration; l; 196 1'23 Niwellber 17 1950 Axplicaon for dotted line A being the record of substantially anhydrous reissue August 19 1957, Selal No'. 679,114 material (0.10%, 0.03 mol, H2O); solid line B being Vthe 5 Claims (Cl 260 586) record of a slightly hydrated ysample (0.84%, 0.24 mol, Matter enclosed in he'avy brackets [l appears in the l5 H2O); while solid line C is the record of an essentially original patent but forms no part of this reissue speciiimonohydrated Sampl (2'8.6% 0'8 m01. H2Q)' rhe cation; matter Printed in italics indicates the additions three spectrograms are considered substantially identical. made by reissue. Solid line D `is the spectrogram Vof the carbon disulfide lvent. Fig. 2 represents the infrared spectrogram of This invention relates to a method for preparing a so l [decachloro-tetrahydro-4,7-methanoindeneone] new ke- 20 the reacilon product of the decachlorqtrahydro`47', tonic compound by condensing two molecules of hexamehallomdneone] CIOCIIOO compound with Ecl Shown chlorocyclopentadiene with the aid of sulfur trioxide to is c-O en ifmeh A lrlld of ttlle cmguund Otmily tn form a hexachlorocyclopentadiene-SO3 reaction product kei lon Othodexal Orocy 9117.311? lege bwt b 3. and hydrolyzing the reaction product to the ketone. .n Wn me s s Own ".s so l me o as o tame The resulting [decachloro-tetrahydro 4,7 methano- 25 m carbqn dlsillde. Solution' The tw? spectrgams are indeneone] keronic compound is useful as an insecticide, Substantlauy ldqltlcal (xpt. for mmor variations due as a fungicide, and as a moth-proofing agent, as disclosed to Smal glumes of lmpurmes).dher.lcel thprgducts and claimed in co-pending application Serial No. 196,121, prepare y. e wo pmcsses are l emma lg' rp' med November 17 1950, now U. S. Patent 2,616,821 resents the infrared` spectrogram, shown asbroken line The exact mechanism Of the new reaction, particularly 30 A? of the .reactlon pioduct of Our-new ketoinc compounfi in its intermediate stages, is not clearly understood, but Wlth acetic mhYdIide as desnbed heremafter 'uns the overall reaction results in a ketonc compound having Spectmgram 1s slmilariy superimposed on the Spectre the empirical formula CMCIIUO [is indicated in the gram S .own as Sovhd Ime B. of the carbon dlsumde S01' equation Set forth below: vent. Fig. 4 represents the infrared spectrogram, shown 35 as broken line A, of the product obtained by reacting f1 our new compound successively with acetic anhydride C C1 and then with ethyl alcohol as described hereinafter.- C1 C C Cl .C1 C/I\(|J C Cl This spectrogram is similarly superimposed on the Vspec- S0 l/Cl trogram of carbon disulde, used as solvent, and shown 2 40 as solid iine B. l

fholyg, \C1 In carrying out our process for preparing the [deca` Cl-o C-C1 /O C-Cl chlorotetrahydro 4,7 methanoindeneone] new ketonc \C/ C (|31\C/ compound above described, hexachlorocyclopentadiene C( \C1 l1:1 il and sulfur trioxide are mixed by Vcharging them, either H h1 233 45 67 F 8 8d hlo o 3 45 simultaneously or separately, to a reaction vessel. After cyclgmhe j'ie'tr'agggojethof" mixing the reactants, the charge may be digested for a indem-LODE short period, sufficient to condense two molecules of.. [The intermediate stages of the reaction are believed hexachlorocyclopentadiene and to form a liquid reaction to proceed somewhat as illustrated below: product of hexachlorocyclopentadiene 'and sulfur trioxide.

f1 i /C\Ci Cl-C--o-Cl Cl-O I Cl -CC1 l/ 2 -I- 2S O:

i Cl Cl-G C-Cl Cl-C -Cl \C/ Cl/ \C1 l \OS01C1 S0101 -I- 4R20 Ci C1 i. C. /.i\c. oi-o/ \o-ooi oi-o l o o-oi 01 o1 I H2O I l 2H2S04 2HC1 \ci )j o1 (L Cl /C-Cl Cl-C\ C-Cl l l 0H OH The liquid SO3-hexachlorocyclopentadiene reaction product thus formed is then hydrolyzed to the [decachloromethanoindeneone] ketone by drowning the reaction product in a relatively large volume of an aqueous drowning medium, preferably an alkaline aqueous medium, for example, in at least about 5 volumes of drowning medium per volume of reaction product.

After addition of the reaction product to the drowning medium is complete, the mixture may be digested for a short additional period, for example a half hour, to insure completion of the hydrolysis.

The product may be filtered at this stage, if desired, but to improve coagulation and ease of filtration, we prefer to lagitate the batch for a short period at a temperature somewhat higher than the drowning temperature, for example at about 90"-95 C. for about a half hour, during which the crystalline product may partially or completely redissolve.

When the drowning has been effected in an alkaline solution, the charge is then neutralized, for example with sulfuric acid, whereupon the crystalline product reprecipitates. The amount of acid added for neutralization should be suicient to bring the mixture preferably to neutrality, or to a very slight alkalinity not exceeding about 0.05% NaOH, as indicated by a pH of 7-8.

After neutralization, the charge is agitated, preferably at a temperature between about 90 C. and about 95 C for about a half hour while maintaining the mixture the neutral point or slightly on the alkaline side.

p The mixture is then cooled, for example to room temperature to insure relatively complete precipitation of the product, leaving in solution the salts formed in the neutralization step, e. g. alkali metal or ammonium chloride and sulfate.

Y Separation of the precipitated product may be effected in any desired manner, for example for filtration, centrifugation, etc., and the recovered product may be dried and ground for storage or use. The final product is obtained in hydrate form as a white or light gray solid. The [decachlorotetrahydro-4,7methanondeneone]ketone of `our invention may exist in all degrees of hydration from substantially anhydrous to an undried gelatinous solid ostensibly containing 67.3 mols H30 per mol anhydrous material. A number of examples-chosen at random-are shown 1n Table I below:

TABLE 1 Mols H10 Sample Weight per Mol Comment No. Percent jAnhydrous H30 Compound 0` 0 Theory tor anhydrous compound. 3. 54 1 .Theory tor mouobydrate;

6. 84 2 Theory for dihydrate. 4. 7B 1. 36 Dried 18 hours at 90 C. 1. 70 0. 47 Dried 72 hours at 90 O. 10. 90 3. 33 Dried 72 hours at 27 C.

The sulfur trioxide used as the condensing agent may be added in any suitable form, for example as liquid or gaseous S03; or dissolved in an inert solvent such as sulfuryl chloride (SO3C13), or in the form of oleum, prefer- I pentadiene, the temperature of the charge is preferably maintained at about 35 C. or above to avoid momentarily delaying the sulfonation reaction with the result that the cumulative reaction may take place with violence at a later stage. Furthermore, when using liquid S03 as a reactant, it is undesirable to exceed about C. during the course of the addition since liquid S03 volatilizes slightly below this temperature. In any event, we prefer to carry out the addition of the reactants at temperatures between about 35 C. and about 70 C. Temperatures above about 70 C. during S03 addition appear to cause an increase in the viscosity of the mixture and to promote undesired side reactions which decrease the yield ofthe desired product. The reactants may be mixed in any desired manner and in any order. However, when operating lon a large scale, it is sometimes desirable to mix the reactants step-wise to aid in controlling the temperature of the exothermic reaction, especially when using liquid S03. In Such `cases it is convenient to add the more Volatile S03 (B. P. 43 C.) to the liquid hexachlorocyclopentadienc gradually or portionwise. A digestion step at a temperature above the reaction temperature, for example about 80 C., may be carried out, if desired, following completion of mixing of the reactants.

The ratio of S03 to hexachlorocyclopentadiene for good yields of reaction product should be at least 1:1, and we have found that a slight molar excess of S03 over hexa-chlorocyclopentadiene, for example l.5:l, improves the yield, and eliminates unreacted hexachlorocyclopentadiene residue in the charge which otherwise would have to be removed from the charge by a separate operating step, such as, for example, steam distillation.

The hydrolysis of the hexachlorocyclopentadiene-SO3 reaction product may be effected, if desired, by simply drowning the mass in water. However, the extremely corrosive nature of the spent acid thus obtained, containing both sulfuric and hydrochloric acids, makes such solutions extremely difficult to handle in metallic equipment. Accordingly, we prefer to carry out the drowning step in a weak alkali solution, for example a weak alkali metal nydroxide solution. Ammonia or the alkali metal carbonates may be used if desired, but are not as satisfactory as the alkali metal hydroxides as they tend to cause foaming ot' i the charge and sometimes gelling of the precipitated product, rendering it ditiicult to separate or filter. The use of alkali metal hydroxide concentrations above about 10%, however, appears to cause considerable thickening upon neutralization. Accordingly, we prefer to employ alkali metal hydroxide solutions of not more than about 10% concentration by weight, for example concentrations of between about 6% and about 8% being satisfactory. The aqueous drowning solution should preferably be warm, for example at least about 40 C. at the start of the drowning operation. The charge of reaction product is added rather slowly to the drowning medium, and the temperature rises somewhat due to the exothermic nature of the reaction. When the temperature has risen to about 60-70 C., external cooling is provided and the remainder of the charge added, preferably while maintaining the temperature between about 60 C. and about 70 C. Upon addition of the reaction product to thc drowning medium, droplets usually form which gradually whiten in color due to the formation of crystalline [decachloromethanoindeneone] product; and these droplets gradually disperse to liberate a tine white crystalline precipitate.

As pointed out above, it is desirable tofollow the drowing step with a digestion step of short duration, for example between about 30 and about 60 minutes, at an elevated temperature, for example -95 C., to insure complete hydrolysis.

In general, the temperature during the drowning operation appears to determine to a considerable extent the physical character of the resulting precipitated product, a digestion period ,at an elevated temperature, e. g. ca. 90 95 C., both befpre and after neutralization aiding MASS intheformation of a crystalline productl which is readily separated from the solution, whereas drowning at lowertemperatures, for example 50-60 C. without a digestion step at the higher temperature indicated above, re'

sults in a gelatinous precipitate which is difiicult to separate from the reaction mixture. Accordingly, we prefer to carry out the drowning and neutralizing operation under approximately the temperature-time conditions illustrated in the schedule yset out in Table II below:

In order to identify the compound prepared according 'to our invention and others described herein, their infrared spectrograms were measured and recorded.

The infrared spectrograms shown in the figures were prepared on a standard infrared recording spectrophotometer designed for measuring and recording the infrared transmission of solids, liquids and gases, comprising a double infrared beam which scans the spectrum through the wave length range 2.0 to 16 microns, one part of the beam passing through the sample under study, the other passing through a compensating cell. lf the sample under study absorbs radiation, the two beams become unequal. The magnitude of this inequality is a measure of the transmission by the sample of the particular wave length, and the record of these differences within the range of wave lengths scanned is the infrared spectrogram, recorded as an ink. drawn line on a chart graduated in percent transmission as ordinates and in wave length as abscissae.

Solid samples, such as the compound of our invention and the related compounds described, are conveniently measured in solution. The spectrograms shown in the figures were all measured by dissolving 0.5 gram of the solid in carbon disulfide and diluting to 1G ml. with the solvent. A small amount of the solution was then introduced into a liquid cell with sodium chloride windows and sealed. The cell was placed in the spectrophotometer in the path of one of the beams as described above.

The infrared spectrogram of any chemical compound serves as an accurate means for identifying the compound. It has been compared with a human fingerprint in its ability to identify a compound with certainty. The characteristic reproducibility of the infrared spectrogram of a given compound is due to the facts that when a molecule is excited by infrared radiation it absorbs energy to a greater degree at some wave lengths than at others, and that the amount of absorption depends on the configuration and upon the linkages of the atoms composing the molecule. Accordingly, the compound prepared according to our invention, and also the other compounds shown in the several figures, are identified and characterized with certainly by their individual spectrograms. The spectrogram of the [decachlorotetrahydro-4,7methanoindeneone] ketom'c CmClmO compound prepared according to our invention, which, as a solid, exists in various degrees of hydration as pointed out above, is the same regardlessof the degree of hydration. This sameness may be explained by the assumption that when the sample is dissolved in they hydrophobic carbon disulfide solvent,A

mosti ofthe water of' hydration is disassocatedifom tliel compound so that what is measured is the spectrogram.A of the product itself or ofi a hydrate containing. only a small amount of water.. Regardless of any explanation, the characteristic spectrogram persists and` is independent` of the degree of hydration (while theV three` spectrograms` of the [decachlorotetrahydro 4,7 methanoindeneone] ketonz'c CIUCIIOO compound shown in Fig. 1 exhibitl slight variations, these variations are not considered' significant).

The following specific examples further illustrate the invention. Parts are by weight except as otherwisel indi cated.

EXAMPLE 1v A charge of 188 parts (.69 mol) of hexachlorocyclopentadiene was cooled to 5 l0 C., and to the agitated" charge was added gradually 940 parts of 60% oleum (containing 565 parts (7.1 mols) of free S03). After addition of all the oleum, which required about one hour, the mixture, whose temperature had risen progressively to about 70 C., was added slowly to a large volume' (5000 parts) of water to dilute the acid. The crude` fdecachloromethanoindeneonel ketonc product precipi- V tated immediately, upon contact of the charge with thev water, as a white solid. The product was filtered from the spent acid, stirred three times with fresh water, and filtered after each water wash, to remove most ofy the sulfuric acid. The product was further purified by dissolving it in 500 parts ethanol, reprecipitating` by` the addition of 500 parts Water, filtering and drying. 126 parts of purified [decachlorotetrahydro-4,7methanoindeneone] CMCZMO ketone hydrate were obtained representing a yield of 72% of theoretical.

EXAMPLE 2 240 parts (3 mols) of liquid S03 were addedl rapidly' to a stirred solution of 818.1 parts (3 mols) of hexachlorocyclopentadiene and 563 parts (4.17 mols) of sulfuryl chloride (SOZCIZ) which was at room temperature. With the addition of the S03, the charge temperature rose from 25 C. to 30 C. The charge was then heated gently for four hours at 80 C., then cooled and'. added with stirring to 5000 parts of water, upon which. a white solid precipitated. The mixture was` stirred for a half hour, filtered, and twice again mixed with water, stirred and filtered. The s'olid precipitated product was dissolved in about 2000 parts of methyl alcohol, decolorized with active carbon, the clarified solution drowned in water to precipitate the product, which, upon filtration and drying, yielded 532 parts of [decachlorotetrahydro-lt,7-methanoindeneone] CmClloO ketone hydrate, corresponding to a yield of 70% of theoretical.

EXAMPLE 3 To 50 parts (0.18 mol) of hexachlorocyclopentadiene' at room temperature (25 C.) was added dropwise with'v stirring 14.7 parts (0.18 mol) of liquid S03 over a periodi of about 15 minutes. After the S03 had been added, the charge was heated to 80 C. for four hours on a water bath. Then the reaction mixture, a dark red viscous" liquid, was poured slowly with stirring into 500 parts of cold water. A white ilocculent precipitate formed whichk was filtered and washed several times with water. This solid reaction product was worked up as described in previous examples to give a final yield of 24.1 parts of [deca-chlorotetrahydro-4,7-methanoindeneone] CmCl'wO ketone hydrate, corresponding to 53% of theoretical.

EXAMPLE 4:

273 partsl (1.0 mol) of hexachlorocyclopentadiene and parts (1.5 mols) of liquid sulfur trioxide were charged simultaneously to a reaction vessel at room temperature (about 25) while agitating. Upon mixing', thetemperature dropped momentarily an increment of about C. due to 'negative heat of solution. The temperature then rose spontaneously to 40 C. due to heat of reaction. tween about 40 C. and about 45 C. for a two hour period while continuing the agitation and while cooling the charge with cooling water circulated through an external water jacket. Following the reaction period, the temperature was gradually raised over a three hour period from 45 C. to 65 C. by external heating. The mixture remained an oily mass throughout the reaction period, ibut became more viscous as the reaction proceeded, the color changing to a dark red. The mixture was then cooled to room temperature and yielded 390 parts of hexachl-orocyclopentadiene-SO3 reaction product, which was dark red in color and had the co-nsistency of molasses.

The hexachlorocyclopentadiene-SOa reaction product was hydrolyzed by slowly pouring the 390 parts of reaction product, obtained as described in the previous paragraph, -into an aqueous alkaline solution containing 3100 parts of water and 200 parts of sodium hydroxide (a 6% solution) at a temperature of 40 C. to 50 C. The addition of reaction product consumed about half an hour. A mildly exothermic reaction ensued, the heat of which was soon dissipated by the large volume of the alkaline solution. When about half of the reaction product had been added, the temperature had risen to 50 C. to 60 C. and thereafter cooling was applied during the remainder of the addition to maintain the temperature between 60 C. and 70 C. The thick droplets which formed upon drowning the reaction product, slowly whitened in color and gradually dispersed to line white particles. After addition of the reaction product was complete, the slurry mixture was digested for 'about one-half hour while continuing the agitation and while maintaining the temperature between 60 and 70 C. The temperature of the mixture was then raised and maintained between 90 C. and 95*l C. for an additional half hour in order t-o insure complete hydrolysis, whereupon considerable of the crystalline product redissolved in the alkaline solution. Then the mass was neutralized with sulfuric acid by slowly adding over a one hour period, parts of H2804 as 100% to a very slight alkalinity not exceeding about 0.05% NaOH, as indicated by a pH of 7-8. During the course of the neutralization, some of the [decachlorotetrahydromethanoindeneone product] CMCIMO ketone separated in gelatinous form making continued agitation dilcult. However, upon continuing the agitation, the neutral mixture began to coagulate and soon the mixture again became white in color due to separation of the solid product. Agitation of the mixture was continued at 90 C. for an additional half hour while maintaining the pH value at the above ligure. The mixture was then cooled to room temperature (about C.) to complete crystallization of the [decachlorotetrahydromethanoindeneone] CMCIMO ketone hydrate. The crystalline product was separated by filtration which was completed in about 10 minutes. The filter cake was washed with water until the filtrate was clear and colorless. The wet filter cake, amounting to 800 parts, was dried in an oven at 110-l15 C. requiring about 36 hours vto drive oft` the water and to bring the cake to constant weight. The dry filter cake amounted to 218 parts corresponding to a yield of [decachlorotetrahydromethanoindeneone] CwClwO ketone hydrate of 86% of theoretical. The dry product was cooled to 50 C. and pulverized.

The products obtained as described in each of the above examples, had infrared spectrograms substantially identical with those illustrated in Fig. l of the drawings.

A portion of [decachlorotetrahydro-4,7methanoindeneone] CIoClmO ketone hydrate obtained as described in the foregoing examples was' purified and dehydrated by repeated vacuum sublimation and analyzed. It had The reaction temperature was maintained be-l the following analysis as compared to theoretical for CloClmO.

The [decachlorotetrahydro 4,7 methanoindeneone] CNCIMO ketone hydrate prepared according to our invention is a white crystalline solid with no appreciable odor. Upon heating in a glass melting point tube by conventional procedures up to 300 C., no tendency to melt is noted. It sublimes when heated in the atmosphere; for example, slight sublimation occurs upon oven drying at ll0l15 C. while upon heating at 140 C. at l-1.5 mm. of Hg pressure, 10-15 of its weight sublimes in three hours. It sublimes with some decomposition when heated in the open atmosphere to 300 C. It is readily soluble in actone, lower aliphatic alcohols, ethers and the like, and also in nitrobenzene and sulfuryl chloride. It is somewhat less soluble in benzene, toluene, hexane and petroleum ether, but is suliciently soluble in warm hexane to allow the use of this material as a recrystallizing solvent if desired. It is virtually insoluble in cold water and only slightly soluble (less than 0.4%) in `boiling water. It tends to gel upon separation by cooling, from hot solutions in hydrocarbon solvents. A satisfactory recrystallizing solvent is %-90% aqueous ethanol from which gelation does not occur. It usually exists as a crystalline hydrate when exposed to atmospheric conditions and is useful for insecticidal, etc., purposes in hydrate form. The compound prepared according to our invention is soluble in, and relatively stable toward, strong caustic solutions such as sodium, potassium, and calcium hydroxides. It is identified with certainty by the infrared spectrogram shown in Fig. 1.

The stability towards caustic materials of the compound prepared according to our invention is of advantage in the use of the compound as a pesticide in combination with lime and other alkaline agricultural chemicals, and in this respect it is superior to benzene hexachloride (BHC) and dichlorodiphenyltrichloroethane (DDT) which decompose readily in contact with alkalis. Furthermore, the compound prepared according to our invention, being volatile under normal atmospheric conditions only at temperatures considerably above those usually encountered in use, has a high residual insecticidal activity, and because of its limited solubility in hydrocarbon solvents is considerably more resistant to dry cleaning than DDT, which is an advantage in the use of the -compound as a moth-proofing agent.

[The compound prepared according to our invention is believed to be the 2,3,3a,4,5,6,7,7a,8,8decachloro 3a,4,7,7a-tctrahydro-4,7methanoindene-l-one, illustrated in the equations set forth above] The method of preparation and the reactions of the compound are consistent with the ketonic structurenamely, reaction with phosphorus pentachloride, with butyricanhydride, with acetic anhydride and the further reaction of the acetic anhydride reaction product with `ethyl alcohol, and formation of a phenylhydrazone. [Strong indications that the ketone group is in the 1 position as shown (and not one of the two other theoretically possible monoketones having the keto group in the 2 or the 8 position) are furnished by the reaction with phosphorus pentachloride and its stability to heat. Proof that the product contains a hexachlorocyclopentadiene rest as part of its structure is shown by the fact that high temperature pyrolysis of the compound yields a substantial quantity of hexachlorocyclopentadiene] Reactions r of the [decachlorotetrahydiome'tlanoin deneone product] CmClwO ketonic compound with the following: Phosphorus pentachloride, butyric anhydride;y acetic anhydride; and the further reaction of the aceticanhydride reaction product with ethyl alcohol are de'-Y scribed in the following examples.

EXAMPLE Five parts of hydrated [decachloro-tetrahydrometlianoindeneone] CIGCZMQ ketone prepared as described in Example 4-puried by solution in methanol, precipitation with water and drying-were mixed with 21 parts of phosphorus pentachloride and the' mixing heated for three hours at 125-150 C. The resulting oily produccy was cooled to C. and drowned in water. The solid material which formed was filtered andy water washed, then washed with methanol to dissolve any unreacted [decachlorotetrahydromethanoindeneone] ketonic compound which might be present, and dissolved in hot benzene. The benzene solution was mixed with a large excess of methanol to reprecipitate the product which was filtered, dried and then recrystallized from isopropanol. Two parts of a hexachlorocyclopentadiene dimer C10Cl12 were obtained. An infrared spectrogram prepared from this product was found to correspond to that shown as broken line A in Fig. 2 and to be identical with the dimer of hexachlorocyclopentadiene prepared by reacting hexachlorocyclopentadiene with aluminum lchloride as described in JACS 71, page 954 (March 1949), in physical properties as well as its infrared spectrogram, shown as solid line B in Fig. 2.

EXAMPLE 6 One hundred parts of the [decachlorotetrahydromethanoindeneone] CMCIIOO ketone hydrate prepared as described in Example 5 recrystallized from methyl alcohol and clarified with active carbon were mixed with 500 parts of freshly distilled acetic anhydride and the mixture was refluxed at 138 C. for six hours. The mixture was then vacuum distilled to remove the bulk of the unreacted acetic anhydride, leaving a slurry which was filtered. The crude solid amounted to 65 parts and melted at 138-140 C. A portion of the crude solid was purified by recrystallizing from high boiling petroleum ether. The resulting purified acetate of [decachlorotetrahydromethanoindeneone] CIUCIMO ketone had a melting point of 142 C. Upon heating with water or dilute acetic acid for two hours at 95 C., it was converted to a solid melting at 191-194 C.

EXAMPLE 7 Fifty parts of [decachlorotetrahydromethanoindene one] CmClloO ketone hydrate prepared as described in Example 4 and purified by recrystallization were mixed with 312 parts of acetic anhydride and the mixture was refluxed for 31/2 hours. After cooling the mixture to room temperature, it was drowned in several times its volume of cold water and allowed to stand overnight in contact with the water. A precipitate formed which was filtered and dried, producing a yield of 36 parts of crude product which melted from 238-245 C. The crude product was recrystallized from isopropanol in the presence of decolorizing carbon, yielding a product melting at 231-234. A farther recrystallization from petroleum ether yielding a product melting at 251255 and apparently being a hydrated acetate of [decachlorotetrahydromethanoindeneone] the CmClmO ketone. It had an infrared spectrogram corresponding to that shown as the broken line A in Fig. 3.

EXAMPLE 8 125 parts of [decachlorotetrahydromethanoindeneone] CwClmO ketone hydrate purified by recrystallization from methanol, after clarification with decolorizing carbon were mixed with 700 parts of acetic anhydride and were heated at 135140 C. for 4V: hours. The reaction mixture was then cooled t-o room temperature, poured inta 4000 parte of eoldf wat-er anaA allowed te stemt inf indeneone]` the' CmClmOr ketone prepared above" was mixed with 800 partsethyl alcohol and gently refiuxed for 20 hours. During the initial portion of the? heating, the mixture remained as a slurry. As reaction occurred, the solid alcoholate reaction' product' dissolved in the alcohol. After refluxingasV described, the solution was evaporated to 350 m1., and cooled to 10 C. to bring" about crystallization of the product. Upon filtration,Vv 62 parts of product were obtained which uponV purification by recrystallization from ethyl alcohol in the presence of decolorizing carbon yielded a purified dialcoholate of [decachlorotetrahydromethanoindeneone] the CIOCIIOO ketone melting at 123'126 C.- rlts infrared spectrogram' was made and is shown as the broken l-ine A in Fig. 4.

The acetate of [decachlorotetrahydromethanoindeneone] the CwClIoO ketone was reacted with methyl alcohol in a manner similar to that described above yielding a methyl alcoholate reaction product melting at 146 C.; and with isopropanol yielding an isopropyl alcoholate melting at 127 C.

EXAMPLE 9 Thirty parts of purified [decachlorotetrahydromethanoindeneone] CIDCIMO ketone hydrate were mixed with 90 parts of butyric anhydride. The mixture was refluxed for three hours at C. The reaction mixture was then treated several times with boiling water, causing separation of an oily layer which finally solidified. 27 parts of solid product were obtained and were recrystallized from ethyl alcohol in the presence of decolorizing carbon yielding a monobutyrate of [decachlorotetrahydromethanoindeneone] the CwClloO ketone melting at 173 C.

While the above describes the preferred embodiments of our invention, it will be understood that departures may be made therefrom within the scope of the specification and claims.

We claim:

l. The method of making a [decachlorotetrahydro4,7 methanoindeneone] ketonic compound having the empirical formula CIOCINO which comprises mixing hexachlorocyclopentadiene and sulfur trioxide at temperatures between about 35 C. and about 70 C. to form a reaction product thereof, and hydrolyzing the reaction product.

2. The method of making a [decachlorotetrahy-dro-4,7 methanoindeneone] ketonic compound having the empirical formula C10Cl100 which comprises mixing hexachlorocyclopentadiene and sulfur trioxide at temperatures between about 35 C. and about 70 C. to form a reaction product thereof, and drowning the thus formed reaction product in at least about 5 volumes of an aqueous drowning medium per volume of reaction mixture to hydrolyze the reaction product to the hydrate of the {decachlorotetrahydro 4,7 methanoindeneone] ketonz'c C10Cl100 compound.

3. In a process for preparing [decachlorotetrahydro- 4,7-methanoindeneone] a ketonc compound having the empirical formula CIQCIMO, the steps which comprise mixing hexachlorocyclopentadiene and sulfur trioxide at temperatures between about 35 C. and about 70 C. to form a reaction product thereof, drowning the thus formed reaction mixture in at least about 5 volumes of water, containing a small quantity of dissolved alkaline material, per volume of reaction mixture to hydrolyze the reaction product to the hydrate of the [decach1orotetrahydro-4,7 methanoindeneone] ketonic CNCIMO compound.

4. In a process for preparing [decachlorotetrahydro- 4,7-methanoindeneone] a ketonic compound having the empirical formula CmClmO, the steps which comprise mixing hexachlorocyclopentadiene and liquid sulfur trioxide at temperatures between about 35 C. and about 70 C, to form a reaction product thereof, drowning the thus formed reaction mixture in at least about volumes of water containing a small quantity of dissolved caustic alkali per volume of reaction mixture to hydrolyze the reaction product to the hydrate of the [decachlorotetrahydro-4,7-methanoindeneone] ketonc CMCIIGO compound.

5. In a process for preparing [decachlorotetrahydro- 4,7-methanoindeneone] a ketonc compound having the empirical formula CloClloO, the steps which comprise mixing hexachlorocyclopentadiene and liquid sulfur trioxide at temperatures between about C. and about 15 C. to form a reaction product thereof, drowning the thus formed reaction mixture in at least about 5 volumes of water containing a small quantity of dissolved caustic alkali per volume of reaction mixture to hydrolyze the reaction product to the Ahydrate of the [decachlorotetra- 20 12 hydro-4,7-methanoindeneone] kezomc CNCIMO compalma', digesting the charge at a temperature between about C. and about 95 C. for at least about 30v References Cited in the le of this patent or the original patent UNITED STATES PATENTS 2,179,809 IBockemuller Nov. 14, 1939 2,481,157 Schmerling Sept. 6, 1949 2,493,009 McBee et al. Jan, 3, 1950 OTHER REFERENCES Newcomer et al.: I. Am. Chem. Soc., vol. 71, pp. 946- 951 (March 1949). 

